Refrigerating apparatus



.I an. 7,

J.v J. NANCE REFRIGERATING APPARATUS originl Filed Aug. i4, 1930 ssheets-sheet 1 04,59. l la 62 42 7 l f2? O "35.2.22 Mm.

HIS ATTORNEYS.

Jan'. 7, 1936- J. J. NANCE i 2,027,245

` REFRIGERATING APPARATUS Original Filed Aug. 14, 1930 3 Sheets-Sheet 2J. J. NANCE I 2,027,245

REFRIGERATING APPARATUS Jan. 7, 1936.

Original Filed Aug. 14, 1930 3 SheetS-Sheet"3 INVENTOR wm JMA/Cf. I BYHIS ATTORNEYS.

Patented Jan. 7, 1936 UNITED STATES PATENT OFFICE nErmGEnATmG APPARATUSJames J. Nance, Dayton, Ohio, assignor, by mesne assignments, to GeneralMotors Corporation, a

corporation o of Delaware Application 14 Claims.

This invention relatestorefrigerating systems and more particularly tothe mechanism for controlling the temperatures produced'by refrigeratingsystems. l

In refrigerating'systems it is customaryto provide some means formaintaining thetemperature within the evaporator or within the com--partment which generally houses the evaporator, x

substantially constant. For instance, in compression systems, that issystems using a motor driven mechanical compressor or pump, this isgenerally accomplished by starting and` stopping the motor, andconsequently the compressor, at predetermined high and'low temperaturelimits.

' In absorption machines, on the other hand, this is compartment to becooled or to the temperature or pressure within the evaporator.

Frequently, however, it is desirable to provide means in conjunctionwith the refrigerating system for obtaining a temperature below thatnormally maintained in the evaporator or withinthe compartment to becooled. For instance, in the freezing of water, sherbets, and-the like,the freezing is more rapidly accomplished at a temperature below thatnornally necessary for maintaining food stuffs in a refrigeratedcondition. To this '.end, the so-called Cold control has been provided,consisting of means for temporarily changing theoperation of the snapswitch to produce a lower average temperature for a predetermined numberof cycles of operation or periods of operation of .the compressor, afterwhich cycles the means functions automatically to reset the apparatus toitsnormal operation. A typical example of such a Cold control is shownin the patent to King. No. 1,658,342, Febru'ary'7, 1928.

v t It has'been.found,`however, in the-use of al Cold control such asdisclosed in the patent to King,l that cycles of operation of thecompressor frequency vary over wide lranges of time. -For instance, onecycle of operation of the compressor may take a considerable length oftime due to the necessity of removing a large amount f August' 14, 1930,serial No. 475,179 Renewed July 11, 1934 i Consequently, in the use ofsuch a Cold control which is adjusted to maintain a lower than averagetemperature for a predetermined number of cycles'or periods of operationof the compressor, it frequently happens that'the apparatus operatesunder this reduced setting of the Co1d`control for a period of time muchlonger or much shorter than necessary to accomplish the results desired.

It is to apparatus for overcoming these objectionable features that myinvention particularly relates, having for one of its objects apparatusor mechanism operating in conjunction with the refrigerating system formodifying the operation thereof` or, in other words, to produce a lowertemperature within the evaporator for a substantially definite period oftime and independent of the number of cycles orperiods of operation ofthe compressor or generator or generator-absorber.`

Another object of the invention is to provide an improved controlmechanism for a refrigerating system of the type in which the controlmechanism is provided for maintaining a predetermined mean temperaturein the cooling unit thereof, having means which can be actuated at willto modify the operation of the system temporarily to produce a dinerentmean temperature of the cooling unit for a definite predeterminedinterval of time and to thereafter automatically restore the system tothe normal control of the T control mechanism.

' mined temperature limits and to provide an auxiliary arrangement inthe control mechanism which may be operated so as to give a considerablerange of modifications of the temperature limits normally supplied bythe control mecha-- -nism and to automatically restore the normal-contro1 of the mechanism from either of the positions which modify thetemperature limits after a predetermineddenite interval of time.

Further vobjects and advantages of the present invention will beapparent from the following description, reference being -had to theaccompanying drawingswherein a preferred form ofthe present invention isclearly shown. In the drawings:

Fig. 1 is a refrigerating circuit embodying the improved control deviceof the invention;

Fig. 2 is 'a front view of the improved control 55 device;

i .I Fig. 3 is a top view of the improved control deg the control;

vice having the cover thereof removed and show-` ing a portion of thecontrol in section;

Fig. 4 is an enlarged view taken on the lines I 4 4 of Fig. 3 showing aportion of the control in a position tomodify operations of therefrigerating system;

Fig. 5 is an lenlarged view taken on the lines 5 5 of Fig. 4 showing astop member;

Fig. 6 is an enlarged View of a portion of the control device taken onthe lines 6 6 of Fig. 8 showing a spring for automatically actuating thecontrol into normal position;

Fig. '1 is an enlarged view of a portion of the control device taken onthe lines 1 1 of Fig. 3 showing the connection of the time` device withFig. 8 is a view of a portion of the c ontrol device similar to Fig. 3showing the control in a released position ready to be actuated intonormal position;

Fig. 9 is a side View taken on the line 9 9 of l sired to maintainnormally a predetermined temperature in a refrigerating element orevaporator.'

In the form of apparatus chosen for illustrating the preferredembodiment of the invention, the refrigerating ,element comprises anevaporator or cooling unit I0 to which a number of contacts I I areattached in-circulatory relation. Any suitable refrigerant, such assulphur dioxide, is supplied to this elementV by means of a compressorI2 which forces the refrigerant into condenser I3 and thence intoa-receiver I4 from which it passes from pipe I5 through a oat controlledvalve, not shown, -into the evaporator I0. The refrigerant, afterboiling off in the evaporator I0 and coils II and performing itsrefrigerating effect in the well known manner, is circulated to thecompressor through pipes I6 and I1. A suitable mechanism is provided forcontrolling the operation of the system, and, -for the purpose ofillustrating the invention, it is shown herein as a switch which is`responsive to pressure conditions' prevailing within the evaporator orcooling unit I0. `This switch may have a flexible orV expansible chamberI8, such as a metallic bellows, the movement 'of which, in response tothe pressure variations in the system, causes the making and breaking ofan electric circuit at the point I9 so as to start and stop4 the motor20 which is used for driving the compressor.

- In the control mechanism,` the bellows I8 is contained within amounting guard 2| `and has' its upper end 22 secured toa lever 23 whichis pivoted at 24. The opposite end of lever 23 extends intoa bracket 25and has a'lever 26 piv- 'oted thereto by a stud 21. 'I'he lever 26 has acam mounted at one end thereof engaging a spring pressed roller 29 whichprovides a snap action` mechanismfor quickly moving an electric contact30 into or `out of engagement with a simi- ,'larA contact r'30a locatedtherebelow. The lever 23 therefore serves as a means for moving theelectrical contact 30 upwardly with respect to the contact 30a inresponse to movement of the measure resoonsive element or bellows Il.The

v cycle of the system. Likewise, if the' resistance -present inventionand consists in placing a recontact 30 is secured to an arm 3I pivotedat 32 and having its other end attached to the lever 26 by an insulatinglink 33. A stud 34 `passes through the lever 26 and through the link 33to hold these parts together and extends upwardly 5 a great distancefrom the lever. The bellows, levers, and other parts are all mountedupon a base 35 to which a threaded stud 36 extends and has springstherearound which abut the base 35 and provide adjustment for thecontrol device. m Under normal operating conditions the bellows I8v isadapted to be expanded or contracted in response to pressures within thesystem for actuating the lever 23 up and down. This movement causes thecam 28 secured to the lever 26 15 to force the spring pressed roller 29upwardly, thus permitting the'cam to travel to the opposite side of theroller. When this movement occurs a snap action isimparted to thelever26 which causes the movable contact 3.9 to quickly engage 20 'ordisengage its operating stationary contact. In

this manner the motor of the system is started and stopped to cause thecompressor to cyclically withdraw refrigerant from the evaporator. Theforegoing mentioned parts of the control device 25 are identical to andoperate in the same manner as the control device shown in the patent toOtto M. Summers, No.' 1,819,979, issued August 18, 1931. y y

'I 'he apparatus is usually adjusted at the fac- 30 tory or in the fieldby a serviceman for such normal operation by suitably tensioning thesprings which surround the stud 36 and in such condition the lever 23will have its upward and downward movements resisted so that Ait willopen or close 35 the circuit of the driving motor 20 only at the maximumand minimum pressure-temperature points for which the tensioncorresponds.

v the serviceman in the'Y eld. This can be accomplished by interposing aresistance tothe downward movement of the lever 23,*the operation of theswitch contacts thus being delayed so that the system will continueoperating for a longer period of time, thereby prolonging the freezingto the downward movement of the lever 23 is increased it will require a.greater effort onthe part of the diaphragm or bellows I8 to pull thelever down into contact breaking position (the descent of lever 23causing the raising of contact 30 away from its corresponding stationarycontact 30a, thus breaking the circuit).

A suitable method of interposing such a resistance is illustrated in theembodiment of the silient obstruction in the path of the downwardlymoving lever 23. A spring 31 is used for Vthis purpose and in thepreferred embodiment `of the invention the spring 31 is coiled andhooked into and carried by a slotted shaft 38 so arranged that one end39 of the spring 31 pro- -jects while thel body of spring 31 is forcedto rotate with the shaft 38 when same is turned. The pin or stud 21extends outwardly from lever 23 and is engaged by the spring 31 in sucha manner that when the lever 23 descends, the pin 21 engaging the springleg 39 will have its downward movement resisted tp an extentcorresponding to the degree to which the spring 31 is wound:

The spring 31 carried by the shaft 38 may 'oe 75 rotatedandwound up sothat a correspondingly greater tension is caused to bear against thedownward movement of 'lever 23. Thus, if the spring is wound in theposition indicated by the arrow beneath the"Co1der as shown in Fig.

2 more and more tension may be exerted against the descent of the lever23. Various degrees of tension may be secured, ranging from a maximum toa minimum and while any intermediate point between these extremities maybe selected as a position at which to station the spring or wind thespring, in adevlce suitable for manipulation, it is preferable to have aselected series of stations to which the spring may be wound.

Thus, as shown in Fig. 2, the front 4| of casing -42 is provided with adial 43 having points represented by numbers at which the spring may bestopped in its rotation or winding. The shaft 38 which carries thespring 31 is rotated in turn by an operating handle orknob 44 secured toa shaft and held in any position by a spring 46 compressed between .thewall ,4I of casing 42 and a plate 41 when the knob 44 is released andpushed inwardly. The plate 41 is secured to the shaft 4,5 so that itwillrotate therewith and is provided with an extension having a button 48secured' thereto.l The button 48 is adapted to be forced into' any ofthe holes 49 provided -in plate 5I which is mounted on the bottom ofcasing 42 by screws 52. It is to be understood that the holes 49 arelocated in alignment with the points designated by the numerals on thedial 43'.

The resilient modifying device just described is so arranged that, whenthe knob or handle 44 is pulled out and turned to cause the leg 39 of'spring 31 to be in the path ofthe downward movement of lever 23, 'amaximum resistance is interposed to the descentof thelever-23. Thisposition is shown in Fig. 3 where the spring carrying shaft handle orknob 44 is in the number.6 operating position. It is evident thatanappreciable drag is presented to the lever 23. The resultof thisretardation of the downward movement of lever 23 will be to, cause theprolongation of the freezing cycle, in other words, .a longerthan-normaloperationofthe compressor.

i Itis evident that the duration of this longerthan normal operation ofthe compressorwill be decreased as the spring is further untensioned,

thatis, as the spring-carrying shaft land handle '44 is moved tosuccessive positions in the clockwise direction opposite thatindicatedbythe o 'arrow beneath the word Colder in Fig. `2.

from arm26 and istherefore ineffective while the V After therefrigerator has been in operation for an appreciable period, aconsiderable amount of .frost will collect around the coils and actsubstantially as an insulator.

\ 'In order to defrost the refrigerating element,

it isnecessary to shut down vtheoperation or discontinue the operationof the compressor and this is effected by completely blocking themovement'of the control mechanism as by interposingjan obstruction tothe downward movement of the lever 26. For this purpose a blocking arm54 is rigidly mounted onthe spring carrying ar' rangement shown in Fig.3. This arm 54 is normally entirely out of the path of the pin extendingrefrigerating system is in operation and while-the resilient modifyingdevice is in any of its eilecr tive positions. By pullingout handle 44 agreat'- er distance than is ordinarily required to 'moveI thev platel41, thebutton 48 will then clear the;

stop pin 56a, stationarily mounted Ion plate 5|,

and. thezhandle- 44 can then be moved in an oppopin.

site direction to the arrow shown in Fig. 2 to the position markedDefrost as shown in Fig. 2 so as tolengage the underside of the pin 34.The apparatus will continue to defrost since the arm 54 arrests thedownward movement of arm 26 by 5i knob 44 is set into any of thepositions to cause longer than normal operation of the compressor,henceas shown in Fig. 3 the knob is in No. 6 position and of course thearm 54 is disposed in 20 a plane above the pin 34 but does not engagethe The dotted -lines in Fig. 4 show the plate 41 and button 48 innumber I, or normal, position of the switch and corresponds to Fig. 2except that 25 it is a cross section immediately behind the front wall4l of casing 42. vThe full line position in 4 shows the switch in itsColder, or number 6, position, and corresponds to Fig. 3.

The following described parts and their operto performthe desiredresults without departing from the invention which I am about todescribe. For instance, these parts may all beconstructed substantiallysimilar to the construction 35 shown in the Summers patent heretoforereferred to but assembled in a different manner.

Manufacturers of refrigerating apparatus have experimented with anddetermined 'approximate- 1y the length of time required to freeze at acer- 40 tain predetermined temperature such substances as water,ice-cream, sherbets, and the .like and are at present publishingbooklets containing various recipes for concocting such substances, to-

. gether with instructions for placing'and leaving 45 the arm or.pointer of the so-called Cold control 'in certain positions to modifythe operations of the apparatus to produce a lower temperature beforemanually returning the pointer to normal position. The user of a' Coldcontrol of this 50 type is always confronted with such hazards, forexample, as that of freezing everythingcontained in .the coolingcompartment of the refrigerator due to the low temperature produced bythe 'evaporator which will occur should they forget 55 to return thepointer of the device back to normal position.

It isftherefore an object of this invention to provide,means foreliminating such hazards in refrigerating 4apparatus l and I haveprovided 60 means whereby the apparatus heretofore de;-

scribed canbe combined with a mechanism for automatically returning thehandle or knob 44 and th parts connected therewith for modifying'thecontrol device to 'normal position or`to65 the position designated bythe numeral l on the dial 43 shown in Fig. 2. 'To this end I provide amember 56 extending through an opening in the rear wall of caging 42Landinto which the shafts 38 and 45 extend andare connected together by,70 a sliding connection 51-.` The member 56 is pro- `vided with a pin58 and is held in acertain position by` the screw-.59 which passesthrough thewall of casing 42. 4Member 56 is provided with a cammingsurfacel which is engaged by the roll- 80. ation can be constructed inany suitable manner* 63 which surrounds the shaft 45 and has its'opposite en'd 64 connected, by a pin 65, mounted near the outercircumference of a wheel 66. Wheel 66 is journaled on a shaft of a clockor chronometric timing device, the mechanism. of v which is not shown.The chronometric timing device may be. anordinary alarm clock or thelike which has a spring wound alarm mechanism adapted to be released ata certain predetermined time to cause rotation of the wheel 66. Theroller 62 also engages a circular plate 1l loosely mounted upon theshaft 45 and adapted to abut a'shoulder 12 provided on shaft 45.. Acoiled spring 13 surrounds thesliaft'd and has one end thereof securedto the shaft 45 and has its other end secured to a pin 14 mounted onplate 5l.- This spring 13 is wound to a predetermined tension` and isarranged to resist-the move-:-

ment of the handle or knob 44, in the directioh shown by the arrowbeneath Colder in Fig. 2, before it has its ends permanently secured.Thus, the arrangement of spring 13 provides a means for rotating theshaft 45 and knob 44 when the timing device releases'to cause movementof roller 62.

The timing device, which may be `an alarm clock, is secured to andwithin the casing v42 by a face 16 having the usual hour and minutehands or pointers cooperating with numerals for designating time. j ofnumerals on the face 16 having a hand'or pointer cooperating therewithfor designating the time at whichthe alarm mechanism may be set torelease. A stem 11 may be'utilized for moving the hour and minute handsor pointers -of the time device. Another stem 18 may be utilizedforimoving the hand or pointer to any desired position of the secondseries of numerals toindicate the'time at which the alarm shouldrelease. The key 19 may be employed for winding the time device. Anotherkey 80 may be uti- 'lized for winding the alarm mechanism. The

time device mechanism and other parts associated Vtherewith are allcontained within the casing 42, which casing is secured to the -base 35of the control by brackets 8l and screws 82.

In order to protect the control, a sheet metal cover 83, see Fig. 2, isprovided. This cover has openings or slots in its side wall, (notshown), to provide means whereby the cover may be placed on the controlwithout striking. the brackets i 8l and the member 56. Suitable lockingmeans or retaining means include the catches 84 secured to springs 85,which springs are in turn fastened tostuds 86 mounted on the base 35.Catches 84 have an outwardly extending mem- ,ber or hook which enters anopeningin the cover 83 and removably secures the cover on the base. Inthis manner it is evident that the control device may be inspected and,if necessary,

adjusted without dismantling the same.

' Having thus described various elementsy of my i improved apparatus,the operation of the mechanism to automatically restore the auxiliaryadjustment device to normal position, or position indi :ated by thenumeral I on dial 43, will nowbe explained. I'n order to set the deviceto any position to resist the downward movement of lever 23 or to modifythe pressures at which the control is adapted to be actuated, the knobor handle 44 may be pulled out sufficiently to remove the button 48 onplate 41 from the opening or hole 49 located in plate 5I. The knob 44,shaft 45, plate 41, and spring 31 can be rotated in a coun- There isalso a second series terclockwise direction into any of the positionsfor causing longer than normal operations of the compressors. After theplate 41 has been moved into any of the positions indicated on the dial43 thisplate el can also be moved back in a clockwise direction to anyof the other positions designated by the numerals, of less value; ondial 43, that is from number 6 position in Fig. 3 to any of thepositions indicated on dial 43 if desired. During this movement thespring 46 will be compressed and will .apply suilicient tension upon theshaft 45 to cause the shaft 45, knob 44, and end plate 4l to moveinwardly when released. It is'therefore apparent that the knob 44 can bemanually moved back from position No. 6 to any of the other positionsindicated on the dial 43 (see Fig. 2) after the device has been "setwithout hindering the operation of the mechanism, for automaticallyrestoring the auxiliary vadjustment device to normal position. Thus, the

spring 46holds'the button 46 in engagement with any of the holes 49,located in plate 5l, at which the knob is set to permit spring 3l to beplaced in the downward path of lever 23 thereby increasing the springtension which the lever 23 must overcome before actuating the electriccontact 36 to interrupt the electric circuit to the motor 20. In thismanner the motor 26 will be caused to actuate the compressor I2 a longerperiod of time than ordinarily required to Aproduce a lower temperaturein the evaporator. Itis to be understood that the sliding connection 5lof shafts 38 and 45 permit the knob 44 and shaft 65 to be pulledoutwardly without moving shaft 38 and parts mounted thereon. 'I'he.wheel 66 will be automatically returned to a position rendering itcapable of moving the yoke 63 and roller 62 sideways, or to the left asviewed in Fig. 3, by engagement of roller 62 with plate 1i, which platewill be forced inwardly by the spring 46 when the device is set in anyof the positions indicated on the dial 43 other than No. 1" and Defrost.The alarm mechanism may be arranged so that the wheel 66 will rotateonly' sufciently to moveroller 62 until it strikes the stop pin 58.Thus, the roller remains on the camming surface 6l of member 56,I sothat it will be in position to always be reset or forced to the bottomof the camming surface when the device is actuated into any of thepositions except normal operating position. After the 'device has beenactuated into any of the various positions, to

cause the compressor to operate longer, the

. device may then be set to automatically return of cycles the apparatusmakes during such pre-l determined time. In order to accomplish theautomatic return of the device to normal position the stem 18 isactuated to set the alarm mechanism so that it will release afteradenite predetermined interval of time. This can be indicated by thesmall pointer on the face 16 of the clock, together with pointersindicating hours and minutes of time. The key 88 is then actuated towind the alarm mechanism to insure its operation at the time for whichit has been set to operate the release. When the desired interval oftime has elapsed the alarm mechanism will release causing the wheel 66to rotate. Rotation of wheel 66 causes the yoke 63 carrying roller 62 tomove sideways and the roller moves upwardly on the caming surface 6I ofmember 56. Engagement of the roller 62 with plate 1| which 2,027,245 tabuts the shoulder 12 n shaft 45 causes shaft this direction until thepointer on knob 44 reaches no!A veo

' the colder positions.

normal position orl until the extension of plate 41 which carries button48 comes into engagement with stop pin 56a, seeFig. 4. The wheel 66 is'adapted to remainin its released `position until the device is `reset,therefore the roller 62 prevents the button 48 from lentering any of theopenings 49 during rotation of plate 41. Rotationof shaft 45 willthereby be' stopped by its engagement with lpin 56a and the spring 46will then force button 48 into the opening or hole 49 in plate 5Idirectly opposite normal position. Rotation of wheel 66, which rotationis caused by movement of yoke 63, in a direction to the right as viewedin Fig. 3 of the drawings, when the roller 62 is set into its positionto release button 48 at a certain time, will tend to vturn the alarmmechanism of the timing device. t isV there- .fore desirable to providemeans on the shaft of wheel 66 which will permit wheel 66 to be rotatedin one direction without disturbing or rotating the alarm mechanism ofthe timing device such as when the apparatus is being set into any of ISuch a means lcan be in the form of a ratchet that rotation of the Wheel66 by the alarm mechanism in one direction will move the yoke 63 androller 62 while movement of the yoke 63 in an opposite direction willnot disturb or rotate the alarm mechanism of the time device. Ratchetarrangements ofthe type described are wellknow`n inl their respectiveart and it is believed to be unnecessary to illustrate how such aconventional arrangement vcan be applied to theapparatus disclosed. Itis to be understood that instead of using an alarm 4clock mechanism, a

ldevice whichA could be set for a predetermined refrigerator and alsoprovided with means for defrosting said evaporator at will.-

While the several forms of embodiment of the invention as hereindisclosed, constitutev a preferred form, it is to be understood thatother forms might be adopted, all coming'withinl the scope of the claimswhich follow.

What is claimed is as follows:

1. A refrlgerating system comprising in combination, a cooling element,means for circulating a refrigerati'ng medium through said element,means for maintaining said element at a` normal predetermined averagetemperature, manually actuatable means for temporarily modifying saidsecond named means to obtain a.

temperature of said cooling element different from the normal averagetemperature thereof,

arrangement connected* to I the shaft upon which the wheel 66 is mountedso.

and chronometrically operated means cooperating with said manuallyactuatable means and controlling the duration of effectivenessV thereof,said chronometrically operated means being operable independently ofsaid rst and said second named means for automatically restoring the lsystem to normal operation.

2. A refrigerating system comprising in combination, an evaporator,means for withdrawing gaseous refrigerant from the evaporator tocondense the same-and to circulate the condensed `refrigerant to theevaporator, and apparatus for controlling said means including mechanismfor obtaining normally a certain average temperature of the evaporator,said apparatus including a selective setting device for selectivelyobtaining a plurality of different average temperatures of theevaporator, said apparatus also including "chronometrically operatedmeans cooperating with said setting device and controlling the durationof effectiveness thereof, said chronometrically operated means beingoperable independently of said first named means and said controllingapparatus for automatically restoring said mechanism .to normaloperating condition.

3. A refrigerating system comprising in combination, an evaporator,means for withdrawing gaseous refrigerant from the evaporator ,tocondense the same and to circulate the condensed refrigerant to theevaporator, and apparatus including mechanism for cyclically startingand stopping said means automatically in response toI certain high andlow temperatures respectively of the evaporator, a selective device fortemporarily modifying the operation of said mechanism to :secure thestarting of the cycles at a plurality of -Iselective lower degrees oftemperature than normally required, said apparatus includingchronometrically operated means cooperating with said device andcontrolling the duration of effectiveness thereof, said chronometricallyoperated means being operable independently of said first' named meansand said apparatus for automatically restoring said mechanism to normal`operating condition, and said chronometrically operated means includingmeans adapted to be adjusted for varying the time of modified cycles. f

4. A refrigerating system comprising in combination, a cooling u nit,means for cyclically circulating a refrigerant medium through said unit,control apparatus for controlling the circulating cycles of said meanswhereby to' cool said unit to `a predetermined average temperature, aselective device Afor temporarily modifying the cycles of operation ofsaid means whereby to obtain a plurality of selective different averagetemperatures in said unit, chronometrically operated means associatedwith said modifying device for controlling the duration of effectivenessthereof, said chronometrically operated means being operableindependently of said Viirstnamed means and said control apparatus forautomatically restoring the system to normal operating condition.

5. A refrigerating system comprising in combination, a cooling unit,means for withdrawing refrigerant from the cooling unit for condensingthe refrigerant and for delivering it again to the cooling unit, anapparatus for controlling said means including a pressure responsiveelement, electric contacts, snap action mechanism for said contacts,manual operating means normally independent of said snap actionmechanism but operable to modify said snap action mechanism to vary the,pressure at which said mechanism is responsive.' without disturbing thenormal adjustment of said apparatus, and chronometrically controlledmeans cooperating with said manual operating means and operableindependently of said iirst named means and said apparatus forautomatically actuating said manual means out of engagement with saidsnap action mechanism after said manual means has been in engagementwith said snap action mechanism for a predetermined periodV of time.

6. A refrigerating system comprising in combination, a cooling unit,means for withdrawing refrigerant from the cooling unit for condensingthe refrigerant and for delivering it again to the cooling unit, anapparatus for controlling said means including a pressure responsiveelement, electri'ccontacts, snap action mechanism/ for said contacts,manual operating means normally independent of said snap actionmechanism but operable to modify said snap action mechanism to .vary thepressure at which said mechanism is responsive without disturbing thenormal adjustment of said apparatus, chronometrcally controlled meanscooperating with said manualoperating means and operable independentlyof said first named means and said apparatus` for automaticallyactuating said manual means `out of engagement. with said snap actionmechanism after said manual means hasy been :in engagement with saidsnap action mechanism .means for varying the time of effectiveness ofsaid 8. Refrigerating apparatus including a refrig- 'y erant liquefyingmeans and a refrigerant'evaporating means, control means for controllingthe operation of the apparatus for providing a-normal refrigeratingtemperature, said control means including selective means for providinglower than normal refrigerating temperatures and selective means forproviding higher than normal refrigerating' temperatures, one of saidselective means including means for retaining it in modified position toprovide a modified temperature and thereafter returning it to normalposition to again provide normal. refrigerating temperatures. f

9. Refrigerating apparatus including an evaporator, means forcirculating a refrigerant through said evaporator, control means forcontrolling said circulating means, saidfcontrol means having a normalaction operation to control said circulating means to maintain a normalrefrigerating temperature in said evaporator, means associated with'said control means for varying the `normal controlaction of said controlmeans-to erant liquefying and evaporating means, control provide a lowerthan normal temperature in said evaporator, means associated with saidcontrol .means for varying the normal control action of said controlmeans to produce a higher than normal temperature in the evaporator, oneof said 5 means associated with the-control means being renderedinoperative after performing its function to thereby permit the controlmeans to automatically return to itsk normal control action.

10. Refrigerating apparatus including a refrigerant liquefying means anda refrigerant evaporating means, control means for controlling theoperation of the apparatus for providing normal ice freezingtemperatures whereby frost accu` mulates upon the evaporating means,said'control vl5 means including selective means for providing lowerthan normal freezing temperatures and selective means for providingtemperatures above ice freezing temperatures to melt frost from'theevaporating means, one of said selective means 20 being automaticallyoperative to return the ap- -paratus to normal ice freezingtemperatures.

11. 'Refrigerating apparatus including a refrigerant liquefying meansand a refrigerant evaporating means, control means for control- 25 lingthe operation of the apparatus for providing a normal refrigeratingtemperature, said control means including selective means for providinglower than normal refrigerating temperatures and selective means forproviding higher 3o than normal refrigerating temperatures, one of saidselective means being rendered inoperative automatically after apredetermined time to return the apparatus'to normal refrigeratingtemperatures.

12. Refrigeratingapparatus including a refrig erant liquefying means anda refrigerant evapo. f

rating means, control means for controlling the operation of theapparatus for providing normal ice freezing temperatures whereby frostaccumu-40 lates upon the evaporating means, said control means includingselective means for providing rlower than normal freezing temperaturesand selective means for providing temperatures above ice freezingtemperatures to melt the frost from 45 the evaporating means, one ofsaid selective means being rendered inoperative automatically wherebyAto return the apparatus to normal ice "freezing temperatures.

13. Refrigerating apparatus including refrigerant liquefying andevaporating means, control means for controlling the operation of theapparatus to provide ka normal refrigerating temperature, said controlmeans including chronometrically controlled means forl varying therefrigerating temperature,. said chronometrically controlled meansincluding selective meansfor providing different temperature variationsfrom. the normal refrigerating temperature..

14. Refrigerating apparatus including ,refrigmeans for controlling theoperation of the apparatus to `provide a normal-refrlgeratingtemperature, said control means including meansl for providinglower thannormal refrigerating '65 temperatures and. means for providing higherthan normal refrigerating temperatures, `vland chronometric means for.controlling one of said two last mentioned means.

JAMES J.NANCE. 70'

